Planetary scientist Nader Haghighipour presented new solar system simulations at the Origins 2026 conference in Paris showing Earth formed through natural physical processes rather than chance.
Haghighipour, a researcher based at the University of Hawaii at Manoa, led a team that executed more than 1,000 random computer models to determine how rocky terrestrial planets emerge within protoplanetary disks. Rather than adjusting initial variables to reproduce the modern Solar System, the researchers allowed standard laws of physics to dictate how each scenario evolved from scratch.
For roughly three decades, models of terrestrial planet formation relied on predefined assumptions regarding how early solid material was distributed around young stars. Haghighipour concluded that this established approach had reached its practical limits, prompting his team to eliminate artificial constraints and re-examine planetary growth from fundamental physical principles.
Simulations track protoplanetary disk evolution
The study focused specifically on the late stages of planet formation inside a protoplanetary disk, the dense, rotating disk of gas and dust that surrounds a newly formed star. Each simulation incorporated a non-uniform quantity of solid material divided into varying distributions of planetesimals, which are rocky building blocks ranging from meters to kilometers in size, alongside larger planetary embryos.
Over simulated timescales, these hypothetical bodies interacted through mutual gravitational forces, colliding and altering orbits until a stable planetary architecture emerged. The resulting models highlighted the extreme sensitivity of planet formation, demonstrating that minor differences in initial conditions yield dramatically different planetary configurations.
Writing in an article published in Universe Today, Haghighipour explained that even a small variation in initial conditions can have a major impact on the final outcome of a given solar system. Despite this chaos and sensitivity, recent computing advancements allowed the team to run complex calculations far faster than before. Simulations that previously required six to eight months of supercomputing time can now be completed in six to eight weeks on modern laptops.
Natural formation of Earth, Venus and Mars
One of the most significant findings occurred at a distance of one astronomical unit, which represents the average distance between Earth and the Sun, equal to about 93 million miles. The simulations showed that an Earth-like planet with orbital characteristics similar to our world emerges naturally within specific scenarios, without requiring researchers to place the planet artificially into the model.
Venus also formed regularly within the simulated star systems. Haghighipour noted that a planet resembling Venus appeared in approximately 28 percent of the simulation runs and successfully preserved its orbit over time. In several scenarios, the simulated planet settled inside the habitable zone of its host star, while in others it landed just outside that boundary.
Mars likewise emerged in multiple simulation outcomes, appearing as a small rocky body positioned close to its actual location in our Solar System. While the study does not suggest that every star system must produce a replica of Earth, the results directly challenge the view that Earth's planetary architecture is the product of an extraordinarily improbable coincidence.
In planetary science, a protoplanetary disk acts as a circumstellar birth envelope containing gas and dust grains that aggregate into planetesimals and planetary embryos over millions of years. The habitable zone, often called the Goldilocks zone, is the orbital range around a star where surface temperatures permit liquid water to persist. The University of Hawaii at Manoa, located in Honolulu, is a major international astronomy center whose Institute for Astronomy conducts extensive modeling of solar system dynamics and exoplanets.
Implications for exoplanets and extraterrestrial life
The demonstration that terrestrial worlds coalesce naturally under physics-based conditions opens fundamental questions about the prevalence of life elsewhere in the universe. If planet formation predictably yields Earth-like bodies in stable orbits, the likelihood of finding habitable environments outside our Solar System increases.
Haghighipour pointed out that Earth-sized planets, including small super-Earths, are commonly detected within the habitable zones of Sun-like stars. Because these rocky worlds appear frequently across astronomical surveys, the researcher said it is reasonable to suggest that terrestrial life might not be exclusive to Earth.
However, detecting actual biological organisms on exoplanets remains beyond current technical capabilities. Haghighipour stated that finding life on other planets is a very complicated endeavor because human technology has not yet reached the level required to detect biosignatures directly.
The new modeling framework provides scientists with another tool to solve how habitable worlds arise. By isolating the exact physical processes that shape Earth-like planets, the simulations help astronomers determine which star systems are most likely to host conditions suitable for life.
